Pneumopericardium is a medical condition where air enters the pericardial cavity. This condition has been recognized in preterm neonates, in which it is associated with severe lung pathology, after vigorous resuscitation, or in the presence of assisted ventilation. This is a serious complication, which if untreated may lead to cardiac tamponade an...
Air between the heart and the pericardium, the membrane wrapped around the heart. ... (12 Dec 1998) ... 
(noo″mo-per″ĭ-kahr´de-әm) the presence of air or gas in the pericardial cavity.
Type: Term Pronunciation: nū′mō-per′i-kar′dē-ŭm Definitions: 1. Presence of gas (usually air) in the pericardial sac.
Pneumopericardium: Air or gas in the space between the heart and the pericardium, the membrane surrounding the heart.
pneumopericardium The presence of air in the plericardial cavity.
air leaks into the sac surrounding the heart.